Unit 10: Energy Challenges // Section 10: Wind Power
Wind power also indirectly taps Earth's solar energy flux, which causes differences in atmospheric temperatures and pressures that drive winds (for more details, see Unit 2, "Atmosphere"). Wind turbines directly harness wind power and convert it to electricity. Today wind power generates less than 0.5 percent of the world's electricity supply, but it is growing rapidly and has several times the growth potential of hydropower. Wind power scales with the area swept by the blades (proportional to the square of the blade diameter) and the cube of the wind velocity. The best locations for wind farms thus are areas with consistently high winds where large turbines can be situated. Turbines can be located both on land and in shallow waters offshore.
Advances in wind turbine technology, such as larger and more durable towers, are making wind power more efficient and economically competitive relative to fossil-fuel-fired and nuclear-generated electricity. Several European countries have made major investments in wind energy, both for domestic power production and as a high-technology export. Most notably, Denmark generates 20 percent of its electricity from wind and is a major supplier of wind turbines around the world (Fig. 18).
Figure 18. Offshore wind turbines near the southwest coast of Denmark
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Source: © Sandia National Laboratory.
Wind turbines generate electricity without producing air pollutants or greenhouse gases. Concerns about the environmental impacts of wind energy center on finding appropriate sites for wind farms. Some critics argue that wind towers mar natural settings, such as ridge lines and coastal areas, while others worry that turbines blades will kill large numbers of birds and bats. Some early wind power installations, such as the turbines in California's Altamont Pass, had significant impacts on birds, but the industry has learned from these cases. Today, wildlife issues can usually be managed with careful siting processes and thorough environmental reviews. Replacing any significant fraction of fossil fuel consumption with wind power will require widespread siting of turbines, so resolving these concerns is a key step for expansion of wind energy.